I'm wondering if that's really the blinking "Blue" that you're seeing. It's very bright. This would indicate (http://docs.spark.io/#/start/leds):
Flashing blue: Listening mode, waiting for network information.
I don't have the Android or IOs app, so I had to set it up over Serial connection (using Windows). This doesn't require the dfu-util or Zadig. It does, however, require a Windows driver file. Follow the instructions from http://docs.spark.io/#/connect/connecting-your-core-connect-over-usb
If you are really flashing white, I would follow the instructions for a factory reset (http://docs.spark.io/#/connect/troubleshooting-by-color-main-led-off-small-blue-led-dim) and then see what happens from there.
Dave O